Railway signaling



July 29. 1924. 1,503,316

L. O. GRONDAHL ET AL RAILWAY S IGNALING I N VEN TOR @X-eJ/VATTORNEY.

Original Filed April 1 Patented July 29, 1924.

LABS O. GRONDAHL, F PITTSBURGH, AND LEMUEL F. HOWARD, OF EDGEWOODv BOROUGH, PENNSYLVANIA, ASSIGNORS TO THE UNION SWITCH & SIGNAL COM- PANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

RAILWAY SIGNALING.

Application filed April 16, 1921, Serial .No. 461,750. Renewed May 18, 1923.

T 0 all whom it may ooncerni Be it known that we, LARS O. GRONDAHL and LEMUEL F. HOWARD, citizens of the United States, residing at; Pittsburgh and Edgewood Borough, respectively, in the county of Allegheny and State of Pennsylvania. have invented certain new and useful Improvements in Railway Signaling, of which the following is a specification.

Our invention relates to railway si naling, and particularly to signaling of the type wherein roadside signals or other traffic governing devices are controlled by polarized track circuits.

e will describe two forms of signaling apparatus embodying our invention, andwill then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a.

diagrammatic view showing one form of signaling apparatus embodying our lnventlon,

wherein the reversal of polarity of the track circuit current is accomplished by electro-- magnetic means. Fig. 2 is a view similar to Fig. 1, except, that the reversal of track circuit polarity is accomplished by light re- ;sponsive cells.

Similar reference characters refer to similar parts in each of the views.

Referring first to Fig. 1, the reference characters 2 and 2 designate the track rails of a railway along which traflic normally moves from right to left, as indicated by the arrow, and which rails are divided by insn-.

lated joints 3 to form a series of track sections A-B, BC, etc.

Each track section is provided with a track circuit comprising a source of current and an electro-responsive.device,-the former being connected across the rails at the exit end of the section, .and the latter receiving current from the rails at the entrance end of the section. 'As here shown, the source of current for each section is the secondary 4 of a transformer which is designated by the reference character T with an exponent corresponding to the location. This secondary is connected across the rails through the medium of a polarity reversing device, as

'mission mains 6 to which alternating signallays, each of which is designated by the ref-' erence' character J with an. exponent corresponding tothe location. Each of these relays comprises a winding and a pair of pole-changing contacts 56 and 57 Considering relay J for-example, the winding 55 is connected across the rails of track section AB, and the contacts of this relay control the polarity of the current supplied to the track rails of section B-O from the secondary 4 of transformer T When section A'B is unoccupied, relay J is energized and currentv of normal relative polarity is then supplied to section BC; when section A--B is occupied, however, relay J is deenergized, so that current of the other or re- Verse relative polarity is supplied to the rails whereas the two field coils 8 and 8" are connected in series across the terminals of a secondary 15 on the adjacent transformer T. I1; will be seen, therefore. that the field coils are constantly energized by current of one relative polarity, whereas the armature coil 9 is energized by current of one relative p0- larity or the other when the track section is unoccupied, and is de-energized when the section is occupied. The parts are so arranged that when a track section such as B.C is occupied, the armature of the electro-responsive device E occupies a middle position to which it is biased: when current of reverse relative'polarity is supplied to the rails of section BC. the armature 9. swings to-the right; and when current of normal relative polarity is supplied to section BC', the armature swings to the left.

Each of the other electro-responsive devices operates in the same manner.

Located at the entrance end of each track nent corresponding to the location.

section are a source of light 12, and three light-responsive cells 13, 13 and 13. The source of light 12, usually an electric incandescent lamp, is supplied with current from the adjacent transformer secondary 15 and is constantly lighted. Each light-responsive cell 13 has the characteristic of varying in electrical resistance in accordance with vari-= ations in the intensity of the light to which it is exposed. It may comprise a substance such as selenium, stibnite, or copper oxide, or it may be what is known as a photoelectric cell in which the active material is usually an alkali metal. The precise nature and form of these cells does not constitute any part of our present invention.

Attached to the armature 9 of each electro-responsive device E is a mirror 11, which is arranged to reflect a beam of light from the adjacent lamp 12 to the adjacent light responsive cells 13 13 and 13 When the armature is in the middle position, the mirror reflects a beam of light from the lamp 12 to the light-responsive cell 13*. When the armature moves to the left-hand extreme position, the mirror reflects a beam of light upon the cell 13, and when it moves to the right-hand extreme position, the mirror reflects a beam of light upon lightresponsive cell 13".

Located adjacent the entrance end of each track section is a signal which is designated by the reference character S with an expo- Each signal in the form here shown comprises three electric lamps G, Y and R, which lamps, when lighted, indicate proceed, caution and stop, respectively. Referring to signal S the circuit for the proceed lamp G is from the secondary 15 of transformer T through wires 16, 17 and 18, lamp G, cell 13 and wire 21 to the secondary 15. The circuit for the caution lamp Y is from secondary 15, through wires 16 and 20, lamp Y, cell 13", and wire 21 to the secondary 15. The circuit for the red lamp R is from secondary 15, through wires 16, 17 and 19, lamp R, light-responsive cell 13, and wire 21 to the secondary 15.

It will be seen from theforegoing, that the three lamps of eachsignal are connected in multiple across the terminals of secondary 15 of the adjacent transformer T. and that one of the light-responsive cells 13 is included in series with each lamp. The lamps and the .cells are so proportioned that when any one of the cells is illuminated by a beam from lamp 12, the signal lamp which is in serieswith such cell will be lighted and the other signal lamps will be extinguished. This result may be accomplished'because of the fact that the electrical resistance of each cell 13 is considerably lower when the cell is illuminated than when it is not. In order to obtain the proper current values it may be found advantageous to interpose a transformer between each light-responsive cell and the corresponding lamp.

It will, of course, be understood that each cell 13 is protected in a suitable manner, so that the only rays of light which may reach the active material or substance of the cell are the rays which are projected by the mirror 11 from the source of light 12.

As shown in the drawingtrack section A-B is occu ied b a ar or train W so of signal S is therefore lighted, so that this signal indicates caution. Relay J is energized, so that current of normal relative polarity is supplied to the rails of section CD, and so it follows that light is thrown on the cell 13 at location D. This causes lamp G of signal S to be lighted so that this signal indicates proceed.

Obviously, sources of direct current could be substituted for the transformers T in Fig. 1. If this substitution is made, no other change in the system is essential, but if desired, the electromagnetic devices E could be polarized by permanent magnets instead of by the field windings 8 and 8*.

Referring now to Fig. 2, the apparatus shown herein is the same as that shown in Fig. 1 except as to the means for reversing the relative polarity of the current supplied to the track circuits. In Fig. 1 this is ac complished by a pole-changing relay having moving contacts, whereas in Fig. 2 it is accomplished by light-responsive cells and means'for selectively illuminating such cells.

In Fig. 2 the pole-changing apparatusv for each section is designated by the reference character K with an exponent corresponding to the location. Referring to the apparatus designated K, the electromagnetic device E is provided with an additional mirror 11*, which throws rays from an additional lamp 12 on light-responsive cells 70 and 70"... When the electroresponsive device E is deenergized the middle cell 70 is illuminated, and when the armature of the electromagnetic device is swung to the right or to the left, the righthand cell TO or the left-hand cell 70 is illuminated.

Current is supplied to the track rails of sectionB-C by a secondary 4 on transformer T as before. The middle point of this secondary is connected with the. upper track rail 2 by a wire 58. The right-hand termition nal of secondary 4 is connected with the lower track rail 2* by wires 59 and 60, lightresponsive cell 7O and wires 61 and 62.

Cell 70 is connected in'm'ultiple with cell- 7 O by means of wires 63, 64 and 65. The left-hand terminaLof secondary 4 is connected with the lower track rail 2 by wire 67, cell 70, and wires 66, 65 and 62. Normally, therefore, the two outer terminals of the secondary 4 are connected with the lower track rail through paths of comparatively high resistance. When light is thrown on the middle cell however, the resistance between the left-hand terminal of secondary 4 and the lower track rail is materially reduced, so that current of one relative polarity, which I will term reverse polarity, is supplied to the rails of the sec- BG. When light is thrown on either of the outer cells 7 O or 70 the resistance of the path between the right-hand termi nal of secondary 4 and the lowertrack. rail 2 is materially reduced, so that current of: the other or normal relative polarity is supplied to the track rails. On account of the fact that light sensitive cells ordinarily have high resistances, it may be necessary in some lnstances to mterpose a transformer between each pole-changer K and the track.

As shown in Fig. 2, track section A B is occupied by a car or train W. The electroresponsive device E is therefore de-energized, so that signal S indicates stop. Cell 70 in the pole-changing device K is illuminated, so that current of reverse polarity is furnished to the rails of section BC.-

Signal S indicates caution and cell 70 of the pole-changing device K is illuminated. It follows that current of normal relative polarity is supplied to section CD so that signal S indicates proceed. In the polechanging device K the left-hand cell TO is illuminated so that current of normal relative polarity is supplied to the rails of the section to the right of location I).

In anapplication filed on even date'herewith by L. O. Grondahl, Serial No. 461,782, filed April 16, 1921, there is shownin Fig. 5 an inductive type of electro-responsive device Q". A device of this type may be substituted for the devices E shown in the present application without any change in the circuits except that the third stator winding 74 would be eliminated and winding 71 avould be connected across the track rails -wh1le windmg 72 would be supplied wlth energy from a local source, such as a sec;-

ondary ofthe adjacent transformer T.

Although we have herein shown and described only a few forms of signaling apparatus. embodying our invention, it is understood that various changes and modifica tlons may be made therein w1th1n the scope of the appended. claims without departing from the spirit and scope of our invention.

one direction or the other, and a signal for said section controlled by said cells.

2. In combinatlon, a section of railway track, means for supplying the rails of said section with current of normal or reversepolarity, a device for said section selective- 1y responsive to the polarity of the current supplied to the rails, light-responsive cells,

means controlled by said device for selectively illuminating said cells. and signalingmeans controlled by said cells.

3. In combination, a section of railway track, means for supplying the rails of said section with current of normal or reverse polarity, a device for said section selectively responsive to the polarity of the current supplied to the rails, two light-responsive cells, means controlled by said device for illuminating one of said cells or the other according as current of normal or reverse polarity is supplied to the rails, and a signal controlled by said cells and arranged to indicate proceed or caution according as one cell or the other is illuminated.

4. In combination, a section of railwaytrack, two circuits for supplyingcurrent of opposite olarities to the rails of said section, a 11g t-responsive cell included in each circuit, and means controlled by traflic conditions in advance of said section for illuminating one or the other of said cells.

5. In combination, a section of railway track, two circuits for supplying current of opposite olarities to the rails of said section, alig t-responsive cell included in each circuit, means controlled by traffic conditions in advance of said section for illuminating one or the: other of said cells. a device for said section selectively responsive to the polarity of the current in the rails, and a signal for said section controlled by said device.

6. In combination. a section of railway track, means including light-responsive cells for supplying current ofdifferent polarities to the rails of said section, and means for controlling the illumination of said cells by trafiic conditions in advance of said section.

7. In combination, a section of railway track, means for supplying the rails of said supplied to the rails, three light-responsive cells, means controlled by said devlce for illuminating the first or the second cell according as current of normal or reverse current is supplied to the device and the third cell when current is not supplied to the device, and a signal controlled by said cells and arranged to indicate proceed, caution or stop according as the first, second or 10 third cell is illuminated.

8. In combination, a section of railway track, means for supplying the rails of said section with current of one polarity or the other, light-responsive cells, means responsive to the polarity of the current supplied 15 natures.

LABS O. GRONDAHL. LEMUEL F. HOWARD. 

